At $2.15 a Gallon, Cellulosic Ethanol Could Be Cost Competitive

Imagine a near perfect transportation fuel—it's clean, domestic, abundant, and renewable. Now imagine that it's also affordable.

Bringing this vision closer to reality was the challenge the U.S. Department of Energy's (DOE) Advanced Energy Initiative presented to the National Renewable Energy Laboratory (NREL) in 2006. NREL met this challenge in 2012 by demonstrating that it is possible to produce cellulosic ethanol—ethanol from non-food plant sources—in a way that is cost competitive with other transportation fuels.

DOE's Office of Energy Efficiency and Renewable Energy's (EERE) Bioenergy Technologies Office selected NREL to work toward the cost target because of the laboratory's strong reputation in biofuels technology.

"NREL is the world's leading institution in biofuels research, analysis, and development," said National Bioenergy Center Director Tom Foust. "I don't think there is another organization that would have been as capable of pulling this off. We have exceptional staff and state-of-the-art facilities."

Samples of biomass catalysts are prepared for characterization in one of NREL's thermochemical laboratories.
Photo by Dennis Schroeder, NREL

After several years of modeling, performing biomass-to-fuels conversion test runs, and compiling and analyzing market data, NREL has been able to demonstrate actual scenarios that meet the $2.15/gallon by 2012 cost goal—the goal the Advanced Energy Initiative set to demonstrate that cellulosic ethanol could be competitive with corn ethanol and conventional fuels.

"It was a concerted effort," Foust said, when explaining the focus required to carry out the six-year run. "It was an unprecedented commitment to a goal by the lab, and to the lab by EERE."

Two Platforms, One Objective

Achieving this goal wasn't just an isolated victory. NREL has been able to meet the cost goal using two separate conversion platforms: biochemical and thermochemical. The biochemical process can produce ethanol at a minimum ethanol selling price of $2.15/gallon. The thermochemical platform demonstrated a minimum ethanol selling price of $2.05/gallon.

The biochemical path involves the degradation of cellulose and hemicellulose are the structural components of plants, into simple sugars through pretreatment and the use of enzymes. Microorganisms then ferment the sugars to ethanol and other alcohols.

The thermochemical process involves gasifying the biomass to "syngas" consisting of hydrogen and carbon monoxide, and then catalytically converting the syngas to ethanol. See the biochemical and thermochemical process reports for more information.

Rising to Meet Market Challenges

NREL researchers worked simultaneously to meet the cost target and establish design platforms the private sector can use to accelerate the commercialization of cellulosic ethanol. And, indeed, the commercialization has begun. Facilities to produce cellulosic ethanol are under construction, including DOE-supported projects led by Abengoa in Hugoton, Kansas; POET in Emmetsburg, Iowa; and INEOS in Vero Beach, Florida.

While these industry investments are significant, Foust believes that cellulosic ethanol may not achieve the significance in the fuels market that industry, the research establishment, and the administration had hoped when it established the cost goal in 2006.

During the six years NREL and EERE worked to meet the goal, markets changed. Domestic ethanol production met the market demand for E-10, and E-15 did not penetrate the market as hoped.

"The biofuels market is in flux," Foust explained. "It goes through boom and bust cycles. The good news: NREL and EERE set an important goal and achieved it. We're recognized as top partners with the industry. Our reputation has never been stronger."

The strength of that reputation and the ability to meet significant goals are providing NREL with new opportunities. Next up: Biofuels stakeholders are working to convert cellulosic feedstocks into high performing drop-in biofuels that are compatible with existing infrastructure and nearly indistinguishable from gasoline, diesel, and jet fuel, and NREL is helping lead the way.